Synthesis and characterization of CrN/Mo2N multilayers and phases of Molybdenum nitride

CrNx, MoNx, CrOx, MoOx and CrN/Mo2N multilayer films were deposited by reactive sputtering. Characterization of the coatings was carried out using XRD, XPS, optical profilometer, and nano-indentation. The oxidation of the thin films was studied as a function of annealing temperature. Tribological characterization of the Cr2O3 and the Mo-oxides was carried out as a function of annealing temperature. The low friction behavior of MoOx and MoNx was demonstrated. The deposition of CrNx and MoNx was also characterized and multilayer deposition of CrN and Mo2N was carried out. The hardness of Mo2N and CrN and the multilayers were shown to lie in the 20–30 GPa hardness regime. The multilayers are stable up to 500 °C in air and up to 1000 °C in argon. Initial friction testing on the multilayer coatings showed an activated self-lubricating mechanism.